Biomarkers of Alzheimer’s disease (AD), such as beta-amyloid (Aβ42/Aβ40), phospho-tau-181 (p-tau-181), or neurofilament light chain (Nf-L), are found in cerebrospinal fluid (CSF) and routinely support clinical diagnostics. The gene discussed is NEFL; the disease is early-onset autosomal dominant Alzheimer disease.